The Optimum non-coherent detector for detecting frequency shift keying (FSK) signals in an AWGN channel (also known as the Maximum Likelihood Detector) was developed for use to achieve a 4 dB sensitivity improvement over that of a discriminator for 4-level orthogonal signaling (i.e., FLEX®) and 3 dB for ReFLEX®. However the simulcast and multipath performance is not optimum with this class of detector. Techniques have been employed where varying the integration window of the correlator significantly improves the simulcast performance. However, narrowing the integration window may result in a sensitivity loss of about 1.5 dB for FLEX® and more than 3 dB for ReFLEX®. Note, an automatic gain controller (AGC) within a receiver block (see a receiver block 8 in FIG. 1) does not solve the problems described above. Thus, a need exists for a method and apparatus that would still significantly improve simulcast performance and preferably remove phase imbalances that may be experienced while only minimally reducing the sensitivity gain offered by the use of the correlation detector. Ideally, this new correlation detector will also improve the performance under multipath channel conditions such as fading.